Pullimosina (Dahlimosina) bladesi sp.nov., an atypical, superficially Pullimosina (Pullimosina)-like species, is described from fens in Ontario and Alberta. Subgeneric classification of the genus Pullimosina is discussed, concluding that the subgenera of Pullimosina can be defined only on characters of the male and female terminalia.

Published studies have shown inconsistent effects of proteinaceous bait sprays against apple maggot flies, Rhagoletis pomonella (Walsh). Explanations of inconsistency could involve the presence of natural food such as bird droppings competing with bait sprays for attraction of flies. Under field, semi-field, or laboratory conditions, we found that: (1) aqueous solutions of 10% proteinaceous bait (Nulure) were significantly more attractive than water to protein-denied but not to protein-provided apple maggot flies; (2) addition of 2% toxicant (malathion 50 EC) did not affect attractiveness of Nulure droplets but did significantly deter feeding by arriving protein-provided flies (though not protein-denied flies); (3) droppings collected from barn swallows, chickens, and unidentified birds on apple trees were significantly more attractive than solutions or droplets of Nulure to protein-denied flies; (4) droppings that were freshly deposited or fresh from cold storage were significantly less attractive than droppings held under ambient conditions for 1 or 2 days; (5) droppings allowed to dry for 1 day at 25 °C, 60% RH were no less attractive than droppings that received water to simulate dew or rainfall; and (6) droppings treated with antibiotics were significantly less attractive than droppings not treated with antibiotics, indicating that bacteria may be involved in generating attractive volatiles. Together, these findings suggest that in situations where natural sources of protein such as bird droppings or insect honeydew are abundant, apple maggot flies may be relatively unaffected by addition of proteinaceous bait to insecticide sprays.

We tested the hypothesis that the pattern of development and growth of a generalist parasitoid wasp varies in different hosts. We reared Ephedras californicus Baker (Hymenoptera: Aphidiidae), a solitary parasitoid of aphids, under controlled laboratory conditions on five kinds of hosts: nymphal instar 1 (24 h old), 2 (42 h), 3 (96 h), and 4 (144 h) of apterous virginoparae of Acyrthosiphon pisum (Harris), and nymphal instar 1 (24 h) of Macrosiphum creelii Davis (Homoptera: Aphididae). Parasitoid dry mass increased with the host instar at parasitization. Females were larger than males although the degree of sexual size dimorphism declined with increased host size. Development time from oviposition to adult eclosion varied non-linearly with the host instar at parasitization, and was shortest in first and fourth nymphal instars. Parasitoids developing in M. creelii gained more mass in less time than their counterparts developing in A. pisum of the same initial size. In low-quality hosts, parasitoids apparently trade off increased development time for a gain in adult mass. A possible explanation of sexual size dimorphism in E. californicus is that large females may be able to overcome aphid defensive behaviours better than small ones.

The alarm pheromone of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is present in the droplet of anal fluid produced by second-instar nymphs when attacked by predators. Because the anal droplet is used in defense against arthropod predators, it was hypothesized that the alarm pheromone (decyl acetate plus dodecyl acetate) acts as a defensive allomone. This hypothesis was refuted by the demonstration that two predators use the pheromone as a prey-finding kairomone. On a leaf arena, Orius tristicolor White (Hemiptera: Anthocoridae) increased its rate of turning in response to the pheromone, and spent 25% of its time within 5 mm of a pheromone source. When given a choice between connected leaf discs containing a pheromone- or solvent-treated wick, Amblyseius cucumeris (Oudemans) (Acarina: Phytoseiidae) spent a greater proportion of time on the pheromone-containing disc, suggesting an arrestment effect.

A seasonal light-trapping study of Culicoides species, in particular C. obsoletus Meigen, was conducted in the Fraser Valley of British Columbia to determine seasonal peaks and first and last appearance of these insects. Culicoides obsoletus is the causal agent of Culicoides Hypersensitivity (CH), an allergic dermatitis in horses, in British Columbia. Trapping at two sites in 1987 showed that C. obsoletus was first trapped in late March, and peaked in early May and again in late June. Small numbers were collected into mid-November. This coincided with the appearance and regression of clinical signs associated with CH in horses in the area. Stabling horses during the peak activity of Culicoides spp. has been recommended to prevent the development of CH. Light-trapping Culicoides both inside and outside stables showed that although fewer insects were caught inside, some (6%) were trapped indoors. A horse kept in an unscreened stable will not be protected from being bitten.

Three emergence trap designs were evaluated for effectiveness in collecting adult Frankliniella bispinosa (Morgan) (Thysanoptera: Thripidae) from beneath and between citrus trees in Florida. Trap A [a wooden-frame 30- by 30-cm (= 900 cm2) square trap with removable Plexiglas® lid coated with Tangle-Trap® adhesive] was effective in trapping F. bispinosa adults whereas trap B [a polyvinylchloride (PVC) round trap with a centered 3.7-mL capacity shell vial] was ineffective. Trap A was as effective in collecting emerging F. bispinosa adults as trap C [a PVC round trap with a 30-cm-diameter (= 706.5 cm2) removable adhesive-coated Plexiglas lid]. Comparative costs for trap construction, maintenance, and insect counting are all higher for trap A compared with trap C. Trap placement beneath citrus trees 15 cm from the trunk or just inside the dripline of the canopy provided similar thrips catches in two citrus grove sites. Both interior and dripline trap positions beneath "navel" orange trees had significantly higher numbers of F. bispinosa than did traps exposed within rows between these trees.

Epizootiological studies of a Nosema sp. in field populations of the grasshopper Chorthippus curtipennis (Harris) were conducted in Madison County, Montana. The average density and percentage prevalence for each modal stage are reported for two sites from 1986 through 1990. Alternating high and low densities of C. curtipennis were observed during even and odd years, respectively. Prevalence of Nosema in C. curtipennis during a high density year was characterized by an increase in prevalence during nymphal development. Furthermore, prevalence of Nosema in C. curtipennis was positively related to host density, suggesting some form of density-dependent transmission.

I examined the relative feeding preferences of five carabid beetle species for terrestrial gastropod prey. Scaphinotus marginatus Fischer, thought to be a snail specialist, discriminated among seven species of potential prey by size and species, with the slug Deroceras reticulatum (Müller) being the most preferred. Scaphinotus marginatus appears to use its elongated and narrowed mouthparts, head, and thorax to prey upon terrestrial snails without having to crush their shells. The relative feeding preferences of four pterostichine generalist predators (Pterostichus adstrictus Eschscholtz, P. pensylvanicus LeConte, P. protractus LeConte, and P. surgens LeConte) for two species of small snails [Discus cronkhitei (Newcomb) and Euconulus fulvus (Müller)] also were examined. Although all four carabids ate E. fulvus in varying proportions, only P. protractus consumed D. cronkhitei. I suggest that snail shell thickness and differing feeding preferences affect which snail species are eaten by these pterostichines.

We present calculations of droplet sizes and product potencies that are theoretically required to deliver a lethal dose of Bacillus thuringiensis in one droplet to larvae of the eastern spruce budworm in aerial spray applications. The calculations are based on estimates of the dose required for 50% and 95% mortality [4.3 and 26.9 International Units (IU), respectively] and of the lowest dose that caused discernable feeding inhibition (0.5 IU) in force-feeding assays with sixth-instar larvae. For products containing 12.7–16.9 billion IU (BIU) per litre, the most widely used potency range, a 150- to 160-μm droplet is needed to deliver an LD95 and an 80- to 90-μm droplet to deliver an LD50, whereas droplets down to 40 μm are expected to cause extensive feeding inhibition. Our calculations suggest that current application prescriptions result in the delivery of a marginally effective dose to the target foliage and that budworm larvae have to ingest multiple droplets to obtain a lethal dose, a process that is thought to contribute to inconsistent spray efficacy. We predict that dose acquisition can be maximized by increasing product potency to 95 BIU/L, which would enable larvae to acquire a lethal dose by ingestion of only one or two droplets in the size range that is most commonly encountered on coniferous foliage (≤ 80 µm) after aerial application.

The insecticide Foray 48B (Bacillus thuringiensis var. kurstaki Berliner) was applied undiluted at 30 BIU per ha to control spruce budworm, Choristoneura fumiferana (Clem.), in a mixed boreal forest stand of balsam fir, Abies balsamea (L.) Mill., and black spruce, Picea mariana (Mill.) B.S.P. When the treatment was timed to coincide with the early flushing of balsam fir shoots, the corrected budworm population reductions were 74 and 52% on balsam fir and black spruce, respectively. This treatment resulted in 19 and 8% defoliation on the two respective species. When the insecticide application was timed later to coincide with the late flushing of black spruce shoots the corrected population reductions were 93% on balsam fir and 72% on black spruce. Defoliation of the two species was 29 and 10% respectively, following this treatment. Larval survival on both species after the spray timed for black spruce (0.8 and 2.2 larvae per 45-cm branch on balsam fir and black spruce, respectively) was significantly less (P = 0.05) than that observed after the spray timed for balsam fir (4.6 and 4.2 larvae per 45-cm branch on the respective host species).The data indicate that the spray timed to correspond with the flushing of black spruce was generally more efficacious than the spray timed to impact on newly flushed balsam fir; nevertheless, the results raise the question as to how B. thuringiensis insecticides impact on early-instar budworm larvae when there is no preferred current year foliage on which the insects can feed.

A double application of 1.25 × 1012 (total 2.5 × 1012) polyhedral inclusion bodies (PIB) of Disparvirus (nuclear polyhedrosis virus) in an emitted volume of 10.0 L per ha gave acceptable control of gypsy moth, Lymantria dispar (L.), larvae in 1988. More aerial spray trials were conducted in 1989 and 1990 to test a reduced dosage and volume of Disparvirus. Dosage on all plots, applied when larvae were mainly in their first instar, was a double treatment of 5 × 1011 PIB per ha, 3–5 days apart, giving a total of 1012 PIB per ha. The aqueous tank mix contained 25% (v/v) molasses, 10% (w/v) Orzan LS, and 2% (v/v) Rhoplex B60A sticker. Emitted volumes of 10.0 L per ha and 5.0 L per ha were each tested on three replicated plots in 1989, and 5.0 L per ha and 2.5 L per ha were each tested on three replicated plots in 1990. In both 1989 and 1990, three untreated check plots were paired with treated plots on the basis of pre-spray egg-mass densities.The treatments were assessed by counts of pupae in burlap traps, estimates of defoliation, and change in numbers of egg masses in the treated and check plots. Better control was obtained with the reduced dosage at 10.0 L per ha and 5.0 L per ha than at 2.5 L per ha. Using the aqueous formulation described above, a double application of 5 × 1011 PIB per ha at 5.0 L per ha applied at the peak of the first larval instar is the current recommendation for control of gypsy moth in Ontario using nuclear polyhedrosis virus.

The pine false webworm, Acantholyda erythrocephala (L.) (Hymenoptera: Pamphiliidae), is an introduced sawfly that is becoming increasingly important as a pest of pine plantations in Ontario. Laboratory bioassays of 10 insecticides, applied to excised pine branches containing eggs immediately prior to hatching, indicated that carbaryl and permethrin at low dosages were efficacious in controlling larvae. Neither carbaryl nor permethrin affected egg hatch, and field trials at various dosages indicated that 500 g AI per ha of carbaryl significantly reduced larval numbers and mitigated defoliation of 1-year-old and current-year foliage. Comparisons of single early (during egg hatch), single late (mean instar about 3.8), and combinations of early and late applications of lower concentrations of both chemicals suggested that the late application better reduced webworm populations. All tested application rates of permethrin and carbaryl provided significant foliar protection, particularly to current-year foliage. Dosages as low as 35 g AI per ha of permethrin and 125 g AI per ha of carbaryl in mistblower applications of third- and fourth-instar larvae may provide suitable protection, depending on management objectives. Ground applications using a mistblower resulted in no differences in efficacy on branches from different vertical strata, but reduced efficacy was observed on branches on the sides of the trees opposite where sprays were applied. Spray drift tests with carbaryl at 500 g AI per ha indicated that some population reduction occurred in trees up to two 2.1-m-spaced rows downwind from treated trees. Thus, each row would not need to be sprayed in operational programs.

The last-instar nymph of the nabid Lasiomerus annulatus (Reuter) is described for the first time and a diagnosis of the adult is presented. Its geographical distribution is detailed and the northern limit of its range in North America is established at 45 °37′N latitude. New phenological and ecological information is provided based on collections made in Québec from 1979 to 1985 and the bioecology is discussed, especially with regard to habitat preferences and phenological cycle.

A new genus, Nitidotachinus, is described in the subfamily Tachyporinae (Staphylinidae) to include the species formerly placed in the Tachyporoides and Impunctatus groups of Tachinus Gravenhorst and Tachinus excellens Bernhauer. The new genus includes 10 species, all previously described, from North America, Japan, China, and Taiwan. All major diagnostic characters for the genus are compared with those of Tachinus and illustrated with scanning electron photomicrographs or line drawings. The following new combinations are created by transferring the species from Tachinus to the new genus Nitidotachinus: N. adachii (Watanabe and Shibata), N. agilis (Horn), N. excellens (Bernhauer), N. horni (Campbell), N. impunctatus (Sharp), N. lanei (Hatch), N. sawadai (Watanabe and Shibata), N. scrutator (Gemminger and Harold), N. tachyporoides (Horn), and N. taiwanensis (Shibata).The 10 species of the genus are redescribed; the aedeagus is illustrated for all species, except N. excellens Bernhauer, known only from a unique female. A key is provided to aid in distinguishing the species and the phylogenetic relationships of the species of the genus are discussed.

Eleven species of metallic-green Coleophora are recognized in the Nearctic Region, including three that are new: C. ladonia Landry and Wright from Florida, C. ramitella Landry and Wright from the northeastern United States, and C. timarella Landry and Wright from Arizona. Three species are introduced from Europe: C. deauratella Lienig and Zeller, C. mayrella (Hübner), and C. trifolii (Curtis); these are pests of clover seeds. Adults are keyed, described, and illustrated, and the species distributions mapped. Host plants are known for eight of the species, for which larval cases are also illustrated and their life history presented. Nearctic species of metallic-green Coleophora represent a miscellany of unrelated groups, here treated together for convenience. Tentative definitions of informal species groups are provided and phylogenetic relationships of the species are discussed.

Scentless chamomile, Matricaria perforata Mérat [= Matricaria maritima var. agrestis (Knaf) Wilmot], is a widely distributed, rapidly spreading and aggressive weed, especially in the three Prairie Provinces. The seed-feeding weevil, Apion hookeri Kirby (Coleoptera: Curculionidae), is widespread and common in its native range in the Palaearctic. It occurs in such differing climates as the Mediterranean in northern Africa and the boreal climate of western Siberia. The weevil was screened for its host specificity. In the laboratory, females oviposited into the flowers of species in six genera of the tribe Anthemideae, and one species in the tribe Astereae. However, the larvae developed only in Matricaria species, and one adult emerged from stinking mayweed, Anthemis cotula L. In a choice test, ovipositing A. hookeri preferred scentless chamomile 93:1 over stinking mayweed. These results confirm host records in the European literature. It is concluded that A. hookeri is a host-specific and promising agent for the biological control of scentless chamomile.

The introduced European weed scentless chamomile, Matricaria perforata Mérat (Asteraceae), is a target for biological control in Canada (Peschken and Sawchyn 1993). As part of this project, the fauna on scentless chamomile in Canada has been investigated (Woo et al. 1991). In 1990, a total of 25 adult Apion weevils were dissected out of 115 flower heads collected at two locations in Antigonish County, Nova Scotia, on 23 August and 4 September. These were identified by D.E. Bright as Apion hookeri Kirby, 1808 (Coleoptera: Curculionidae). The weevil had not been recorded previously in North America.

The two-spotted spider mite, Tetranychus urticae Koch, is an arrhenotokous species (Helle and Bolland 1967). Mated females produce both male and female offspring; unmated females produce only sons. Although there is no “normal” sex ratio for spider mites, a ratio of one male to approximately three females is often found in many tetranychid species (Wrensch 1985). The exact mechanism of the female-biased sex ratio is not fully understood, but previous studies have demonstrated several factors affecting the sex ratio in spider mites. In this report, we analyze the effects of maternal density, age, and the interaction between these factors on female daily fecundity and offspring sex ratio in T. urticae.